How does modern living contribute to vitamin D deficiency or insufficiency?

Dariush Mozaffarian, MD
Internal Medicine
Humans first evolved near the equator in Africa, where the sun shines directly overhead for much of the year. Our ancestors there wore little or no clothing and therefore probably produced tens of thousands of IU of vitamin D each day. Heavy pigmentation protected the deeper layers of their skin from sun-induced damage. As some groups of humans migrated away from the equator, their skin lightened to enable faster vitamin D production.

For centuries, people typically spent plenty of time outdoors during much of the year. But in the last 300 years, more people began working indoors, and in the last 100 years, began riding in cars. (Not only do cars shield people from the sun, they also contribute to air pollution, which screens out some of the ultraviolet [UV] radiation that reaches Earth.) In the past few decades, putting on sunscreen has become de rigueur before heading outdoors. And in sharp contrast to the trend favoring the "healthy tan" in the mid-20th century, many Americans now intentionally avoid the sun. All of these changes mean that some people are getting less of the vitamin D that our bodies need.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.